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Topic: looking for hi-perf cb450 parts (Read 6009 times)

I'm looking for some second-hand parts for a hi-perf cb450 engine, if any of you racing guys know anyone with a blown up engine or unused parts lying around. I have 12th over pistons already, and will port the head myself. I'm looking for cams, valve spring conversion, and rods primarily. Of course if there's a dry clutch conversion burning a hole on someone's shelf...

I'm looking for some second-hand parts for a hi-perf cb450 engine, if any of you racing guys know anyone with a blown up engine or unused parts lying around. I have 12th over pistons already, and will port the head myself. I'm looking for cams, valve spring conversion, and rods primarily. Of course if there's a dry clutch conversion burning a hole on someone's shelf...

That valve spring conversion can be tricky Paul. There were problems with the inner valve spring rubbing on the guide seal and destroying it. Maybe Kibblewhite or Hanson could give you more on that.

That's the bit Mike's talking about that I mentioned Paul - there's barely enough meat in the head to convert them and if you're not used to doing them you can quickly end up with a big pile of scrap...

i keep hearing that the 500 head is "better," but i don't know why. i know you mentioned not knowing specifically simon, but i wonder if the 500 head has more material in this area making the conversion easier. i'll call kibblewhite, hanson, or one of the other guys offering it before i start, for sure. i noticed m3 offers the conversion kit with new valvesm ti retainers, etc.. maybe mark will notice this thread and pipe in.

Mentioned on this thread is the fact that a CB450/500 is very expensive to make fast. Due to the very 1960's cylinder head design you have to run a very high dome on piston to get compression, added to that one must deal with the very steep valve angle. 500 head is exactly the same in all respects as the 450 head, save for it has ordinary valve seats vs the 450 which has a "skull" type iron/steel dome sunk into the head. 500 head is the best to use.

Right now would be the time to get yourself a CB350 Honda twin and go that way, as you will be spending 3X's money to get almost the same performance with 450/500 twin.

I did the work up with KPMI to make the 5mm valve spring conversion kit. Not anyone from Team Hansen had anything to do with that. Very nice kit, but not worth doing unless you remake (ie: machine cams for adjustable sprockets) both cams and go to 2 spark plugs per cylinder.

Next you will need to machine head for two spark plugs per cylinder to sped up flame path travel time for your ignition will per 45-50 BTDC!

Pistons larger than 72mm will need liners machined and installed as standard liners will distort and cause ring sealing problems.

You must move ignition from camshaft end to end of crank or your timing will vary enough, due to cam chain length/stretch enough to cause problems. This relocation makes the bike race-only...no street use, as you can run no AC generator.

A better oiling system is also a good idea and out friend in Italy is the way to go in that department.

Also, if you are to run in top of class, must have Nova 5 speed (if you can find one) or newer 6 speed close ratio gear box.

I can build you a complete engine ready to run at front or could you consider another bike for this class? I also can supply all parts/services you will need for this effort.

+1 on the cost Mark is talking about for a top CB450 engine. Mine isn't as modified as it could be as I'm still on standard (NOS) rods but I'm into my engine for probably near £10,000. Is it worth it? Hell yes and with a lot of those hot parts already on sale at M3, it's just a case of saving those pennies

first i should mention that this will not be a race bike. i had originally intended it to be so, but decided the 350 sitting in the corner would be a much better candidate as you mentioned, not to mention the fact that i have my 550 race bike that needs attention before the coming season.

this project is just an excuse to use the tony foale motorcycle kinetics software i recently purchased and design a frame/suspension around an engine i have convenient to use. the 450 i have is a total rustbucket i got for free, perfect for the experiment. we will be fabricating the frame and swingarm, and using a modern front end with ohlins or comparable shocks. the bike will be more of a modern classic street bike type thing, but i'd eventually like to build a frame around something to race. the guy i'm building it with races in mini classes on a kx65 and an nsr65... i'm trying to get him out on the big track.

i picked up a +3mm piston kit with jugs already bored to spec locally for very cheap, and figure while i'm rebuilding the engine i might as well do whatever else i can (and can afford) while i'm in there. so ultimate performance for the track is not needed. i'd like to do what's sensible.

mark- really nice stuff on your site. can you sell me a couple wrist pin buttons? the kit i got came missing two..

Another way to do a CB450/500 is to leave most of it alone. This works well for hot street performance. While it will not light the world on fire...it does give this engine some get up and go without sacrificing reliability. Open up exhausts as much as you can stand the extra noise. Get some 32mm Mikuni's on it with air cleaners or stacks, depending on your riding conditions, then I have a great cam to use on intake side only (ex has too big of ports so stock cam works well on that side) and this cam works just fine with torsion bars. I also have a good electronic ignition to fit where OEM points were located.

Let me know if I can help.

M3

PS: Did you know that the 450 was to be a 350cc engine, until Bob Hansen of Honda told the Japanese that 'mericans' liked BIG engines! That is why it is not easy to make bigger without more massive amounts of $$$ being thrown at it. Also, CB350 is really a only 325cc engine...as it was to be a CB250..like over in UK and Canada. Hansen and sales staff at "merican Honda USA told the factory that bigger is always better over here.

Another way to do a CB450/500 is to leave most of it alone. This works well for hot street performance. While it will not light the world on fire...it does give this engine some get up and go without sacrificing reliability. Open up exhausts as much as you can stand the extra noise. Get some 32mm Mikuni's on it with air cleaners or stacks, depending on your riding conditions, then I have a great cam to use on intake side only (ex has too big of ports so stock cam works well on that side) and this cam works just fine with torsion bars. I also have a good electronic ignition to fit where OEM points were located.

Let me know if I can help.

M3

PS: Did you know that the 450 was to be a 350cc engine, until Bob Hansen of Honda told the Japanese that 'mericans' liked BIG engines! That is why it is not easy to make bigger without more massive amounts of $$$ being thrown at it. Also, CB350 is really a only 325cc engine...as it was to be a CB250..like over in UK and Canada. Hansen and sales staff at "merican Honda USA told the factory that bigger is always better over here.

Thank mark, I'm sure I'll need something from you before long. I have the mikunis already, as well as the big bore. The exhaust will be fully custom, so I can make it flow as well as I want. Seems like the intake cam is what I really need then.

I knew that the 250 and 350 share everything but sleeve/bore size, but I didn't know that about the 450. Interesting stuff. Gotta say though, they did a pretty damn good job on the 350 in terms of power and reliability.

Of all God's creatures there is only one that cannot be made the slave of the lash. That one is the cat. If man could be crossed with the cat it would improve man, but it would deteriorate the cat.Mark Twain - Notebook, 1894